This article examines the impact of authoritative parenting, parental involvement in schooling, and parental encouragement to succeed on adolescent school achievement in an ethnically and socio-economically heterogeneous sample of approximately 6,400 American 14–18-year-olds. Adolescents reported in 1987 on their parents' general child-rearing practices and on their parents' achievement-specific socialization behaviors. In 1987, and again in 1988, data were collected on several aspects of the adolescents' school performance and school engagement. Authoritative parenting (high acceptance, supervision, and psychological autonomy granting) leads to better adolescent school performance and stronger school engagement. The positive impact of authoritative parenting on adolescent achievement, however, is mediated by the positive effect of authoritativeness on parental involvement in schooling. In addition, nonauthoritativeness attenuates the beneficial impact of parental involvement in schooling on adolescent achievement. Parental involvement is much more likely to promote adolescent school success when it occurs in the context of an authoritative home environment.